In a procedure for decorating an article such as applying printing thereto as for example by means of offset printing, in which the article is moved on an article carrier along a transport path through one or more treatment stations, in many cases there is a need for the article which is carried by the article carrier to be fixed in a given position in the article carrier accommodating the article, during the transportation phase and also during the decoration phase which, as indicated, may for example include applying printing to the article as by means of offset printing. That is the case in particular when a plurality of printing operations are implemented in succession and the individual partial images which go together to constitute the definitive image have to be oriented in relation to each other in a given manner in order thereby to achieve a good print quality. Frequently in that respect the procedure adopted is such that, after the article has been received by the article carrier, the article is initially subjected to an alignment operation therein to put it into the correct orientation. In the case for example of CDs, that can be effected by a bar or mandrel being passed through the central hole in the CD and bringing it into a given position relative to the article carrier and thus relative to the treatment stations, that given position then being subsequently maintained in the course of further transportation movement and during the following treatment operations, by means of a reduced pressure which is caused to act on the article such as the CD. Hereinafter that reduced pressure can be referred to generally as a `vacuum` although it will be noted that the reduced pressure will normally be not more than between 0.2 and 0.3 bar below the ambient air pressure.
As the article carriers in which the vacuum must be operative to hold the respective articles in the correct position therein move with respect to the frame structure of the machine or apparatus and as the vacuum has to be transmitted from the frame structure of the machine or apparatus to the moving article carriers, this requirement generally entails the adoption of complicated design configurations which are also susceptible to wear, as it is necessary, at at least one location in the apparatus, to afford a connection, which enjoys sealing integrity at least to some extent, as between a stationary vacuum duct or conduit, for example in or on the frame structure of the machine or apparatus, and a vacuum conduit in the moving article carrier. As apparatuses for applying decoration or printing to articles are generally provided with a plurality of article carriers in order to achieve a high level of production output, it will be appreciated that supplying the vacuum to the article carriers is in every way a source of considerable complication in the machine. As an example in this respect attention may be directed to U.S. Pat. No. 5,165,340. In the machine described and illustrated therein, the article receiving means are disposed on a rotating table coaxially with the axis of rotation, so that the articles are moved along a circular path of movement.
In the case of apparatuses involving a path of article movement which is of a configuration that differs from a circular path, the feed of vacuum to the individual article carriers is even more complicated, if not entirely impossible. That applies for example to the apparatus known from EP 0 581 378 A1 for decorating an article, having at least one article carrier for carrying the article, which is movable along a linear transport path between a station in which the article is received by the article carrier and a station in which the decorated article is removed from the article carrier. In that apparatus, orientation of the article carrier in the appropriate position is effected by a centering roller which runs in a guide, while orientation of the article in the appropriate position is additionally implemented by a bar which is passed through the central hole in the article which is in the form of a CD. Those arrangements for orienting and fixing the article to which printing is to be applied are not sufficient to achieve the quality of print image that is required nowadays. In addition, the impression cylinder for applying printing to the article has to be provided with a special recess into which the projecting bar engages during the printing operation.